In-line continuous yarn formation process for making three-dimensional crimped nanofiber functional yarns

Abstract

The present application belongs to the field of functional spinning technology, and particularly relates to an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. The present application in-situ couples a solution jet spinning process with an embedding spinning and drawing process. A jet device is arranged above a bunching area of a drawing frame. Spinning solution is extruded through a coaxial gas-liquid channel. Three synergistic effects of high-speed airflow turbulence, fiber strip drag shear force and solvent evaporation internal stress induce exogenous nanofibers to form a three-dimensional crimped network structure and coat the surface of the base fiber strip. Interface locking is achieved through mechanical extrusion anchoring of the drawing frame, and the finished functional yarns are obtained through subsequent spinning and forming processes. The present application does not require a post-finishing and setting process, and can realize online continuous production of spinning and functional modification. The process is simple, the production cost is low, the nanofunctional layer has good washing resistance and friction-induced shedding performance; the product has a large micro specific surface area, can endow the yarn with multiple functions such as sensing, antibacterial and adsorption, and has a wide range of raw material adaptation.

Description

Technical Field

[0001] This invention belongs to the field of functional spinning technology, and particularly relates to an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. Background Technology

[0002] With the rapid development of the functional textile industry, nanocomposite yarns with special microstructures and multifunctional properties have become an important research direction in the field of high-end textile materials. Conventional functional yarns are generally prepared using processes such as fiber chemical modification, functional powder blending, filament wrapping, or post-finishing impregnation. These processing methods usually have technical problems such as limited functional load, insufficient interfacial bonding strength of functional layers, cumbersome process flow, poor production continuity, and difficulty in large-scale mass production.

[0003] Solution jet spinning is a novel technology for preparing micro and nanofibers, boasting advantages such as wide applicability of raw materials, low energy consumption, simple equipment structure, high forming efficiency, and in-situ deposition molding. It can prepare various functional nanofibers, providing a promising technical approach for the functional modification of textiles. Coupled with mature traditional spinning processes, online in-situ loading modification of nanofibers during the spinning process can effectively compensate for the shortcomings of traditional functional yarn preparation processes, and is of significant research importance for improving yarn structural properties and product added value.

[0004] Currently, a certain manufacturing technology system has been established for three-dimensional crimped functional yarns, but there is still room for improvement in terms of microstructure, functional stability, and industrial continuous adaptability. A detailed analysis based on existing similar patent technologies is as follows:

[0005] Publication number CN122105708A discloses a self-crimping high-loft yarn based on high-shrinkage-difference fiber blending and its preparation method. This technology relies on blending matrix fibers with different heat shrinkage properties, combined with a wet heat finishing process, to utilize the shrinkage differences of the matrix fibers themselves to form a crimped yarn structure. This crimped structure is generated solely by the deformation of the matrix fibers, resulting in a limited range of adjustable crimp morphology and structural controllability. Furthermore, the process depends on subsequent wet heat setting steps, making it impossible to achieve fully online continuous spinning. Simultaneously, this approach only improves yarn loft and cannot construct nanoscale functional structures, resulting in a single yarn function and limited scalability.

[0006] Publication number CN108823720A discloses a yarn with a three-dimensional structure and its production method. The yarn has a three-dimensional shape obtained by spinning a variety of matrix fibers and then performing a finishing process. The three-dimensional structure comes from the mechanical twisting of the matrix fibers and the rebound effect after finishing and setting. No external functional structural load is introduced. The yarn only has basic fluffy and breathable properties and does not have the special effects brought by nanomaterials. In addition, the whole process requires multiple finishing and setting processes, which is relatively complicated and not well adapted to the traditional online continuous production mode of spinning, thus affecting the production efficiency to a certain extent.

[0007] Publication number CN119177509A describes a three-dimensional crimped yarn and its preparation method. It relies on the alternating arrangement of knitted loops to form the yarn crimped structure. The process system is limited to the knitting field and is difficult to adapt to various spinning production lines with wider applications, resulting in insufficient process versatility. Furthermore, its crimping is a macroscopic loop bending and forming process, which does not have a nanoscale three-dimensional microstructure. Therefore, it cannot endow the yarn with multiple additional functions such as antibacterial properties, sweat sensing, and adsorption filtration, thus limiting its practical application scenarios.

[0008] In summary, current technologies for preparing three-dimensional crimped yarns still have significant shortcomings. Existing crimped structures are all based on differences in thermal shrinkage of matrix fibers, mechanical twisting and rebound, or macroscopic knitting structures, failing to form a three-dimensional crimped microstructure independently encapsulated by exogenous nanofibers. This makes it difficult to leverage the multifunctional properties of nanomaterials, resulting in relatively limited structural controllability and functional expansion. Furthermore, traditional preparation processes largely rely on subsequent setting and finishing auxiliary processes, making it difficult to integrate into traditional spinning production lines for integrated online continuous preparation. This leads to poor process adaptability, insufficient product consistency, and significant challenges in large-scale mass production. In addition, traditional functional modification methods lack reliable mechanical anchoring structures, resulting in weak bonding strength between the functional layer and matrix fibers. These layers are prone to detachment and failure during spinning, weaving, washing, and friction use, leading to unsatisfactory product signal stability, wear resistance, durability, and long-term functional performance. Based on these shortcomings, it is necessary to optimize and improve existing spinning and forming processes, refining the preparation system of three-dimensional crimped yarns from the perspectives of forming mechanism and production process, to enhance the structural stability, functional durability, and industrial application value of functional yarns. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is to provide an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. This method enables online continuous production, has strong structural controllability, effectively improves the bonding strength between the nanofunctional layer and the matrix fiber, and gives the nanofunctional layer excellent water resistance and abrasion resistance. At the same time, the overall process is simple, the production cost is low, the product has excellent comprehensive performance, and the advantages for industrial application are significant.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an online continuous spinning method for preparing three-dimensional crimped nanofiber functional yarn, including fiber raw material selection, opening and cleaning, carding, sliver forming, drawing and drafting of sliver, and subsequent spinning and forming processes, wherein nanofibers are loaded in situ in the bundling area of ​​the drawing frame during the drawing process, and the specific steps are as follows:

[0011] (1) Preparation of solution for jet spinning: Dissolve the fiber-forming polymer in the corresponding solvent and stir thoroughly until the system is homogeneous and stable to obtain the spinning solution;

[0012] (2) Preparation and delivery of matrix fiber sliver: The carded sliver obtained from the previous spinning process is fed into the drawing frame and then sent to the bundling area for waiting through the feeding mechanism and the roller drafting zone;

[0013] (3) In-situ spinning and coating at the drawing station: The spinning solution obtained in step (1) is spun into nanofibers using a solution jet spinning device; the nanofibers form a three-dimensional crimped structure under the synergistic effect of high-speed airflow turbulence, drag shear force of the moving fiber strip, and internal stress of solvent evaporation, and are directionally deposited and coated on the outer surface of the running fiber strip to obtain a nanofiber / matrix fiber composite fiber strip; after the composite fiber strip is bundled and gathered, it is subjected to 1 to 2 drawing and compaction to strengthen the interface bonding, and then twisted and shaped by subsequent spinning and forming processes to obtain a three-dimensional crimped nanofiber functional yarn.

[0014] In the above-mentioned method for continuous online spinning of three-dimensional crimped nanofiber functional yarn, the mass fraction of the fiber-forming polymer in the spinning solution in step (1) is 3-45 wt%; the fiber-forming polymer is at least one of cellulose, chitosan, polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyetheretherketone (PEEK), polyethersulfone (PES), polyurethane (PU), polyamide (PA), and polyvinylamide; the solvent used is N,N-dimethylformamide (DMF) or deionized water.

[0015] The above-mentioned three-dimensional crimped nanofiber functional yarn online continuous yarn forming method, in step (2), the matrix short fiber raw material after pre-spinning is cotton short fiber, viscose short fiber or polyester chemical fiber short fiber.

[0016] In the above-mentioned method for continuous online yarn forming of three-dimensional crimped nanofiber functional yarn, in step (3), the solution jet spinning device is fixedly installed above the bundling mechanism of the drawing frame, and the device is installed vertically to the fiber strip in the bundling area at a height of 30-100cm.

[0017] The above-mentioned method for continuous online spinning of three-dimensional crimped nanofiber functional yarns has the following process parameters in step (3): jet gas pressure 0.05~0.25MPa, spinning solution extrusion speed 0.01~0.6mL / min, spinneret orifice inner diameter 0.10~0.80mm, spinning environment temperature 15~35℃, and spinning environment relative humidity 30%~65%.

[0018] In the above-mentioned online continuous yarn forming method for three-dimensional crimped nanofiber functional yarn, the exogenous nanofibers are embedded in the gaps of the matrix fiber surface in a three-dimensional crimped form and anchored by mechanical extrusion during drawing, making them difficult to peel off during spinning, weaving and washing processes; the three-dimensional crimped structure is independently formed by exogenous jet nanofibers.

[0019] In the above-mentioned online continuous yarn forming method for three-dimensional crimped nanofiber functional yarn, the subsequent spinning and forming process is any one of ring spinning, rotor spinning, vortex spinning, and air-jet spinning.

[0020] A three-dimensional crimped nanofiber functional yarn is prepared by the online continuous yarn forming method of in-situ loaded nanofibers as described in any one of the above. The yarn surface is coated with a three-dimensional crimped exogenous nanofiber porous network and can be used as a flexible sensing yarn for sweat monitoring.

[0021] A functional fabric is woven from the above-mentioned three-dimensional crimped nanofiber functional yarns; the fabric can be prepared as an antibacterial fabric, a conductive sensing electronic fabric, a self-healing flexible fabric, or a high-adsorption filtration fabric.

[0022] The advantages of this invention for the online continuous yarn forming method of preparing three-dimensional crimped nanofiber functional yarns are as follows: This invention overcomes the technical limitations of traditional crimped yarns that rely on matrix fiber deformation and external coating modification of functional layers. It innovatively embeds solution-jet nanospinning in situ into the traditional spinning and drawing process, constructing an exogenous three-dimensional crimped independent coating structure of nanofibers. Furthermore, it utilizes mechanical extrusion and anchoring in the drawing process to achieve integrated composite molding of the nanofunctional layer and the matrix yarn. Through the synergistic effect of high-speed airflow turbulence, fiber shearing force, and solvent evaporation stress, this invention constructs a three-dimensional crimped nanofiber functional network in situ. This improves, to a certain extent, the technical problems of traditional crimped yarns, such as lack of nanofunctional structure, insufficient interfacial bonding strength, easy detachment of functional layers, and difficulty in online continuous production. It effectively balances the controllability of yarn microstructure, stability of functional use, and adaptability to industrial production, and can produce three-dimensional crimped nanofiber functional yarns with stable structure, good comprehensive performance, and suitability for large-scale processing.

[0023] Compared with the prior art, the present invention has many outstanding technical advancements, and the specific beneficial effects are as follows:

[0024] 1. Based on a physical anchoring and locking structure, this invention significantly improves the structural stability and service durability of yarn. Unlike traditional matrix self-crimping and surface coating modification methods, this invention uses in-situ deposition combined with multiple mechanical compaction processes to embed and interlock three-dimensional crimped nanofibers into the gaps between the matrix fibers, forming a stable mechanical locking structure. This fundamentally improves the problems of weak interfacial bonding and easy detachment and failure during washing and friction in traditional functional layers, greatly enhancing the long-term functionality and weaving stability of the yarn.

[0025] 2. Integrated process design enables continuous production and reduces manufacturing costs. This invention directly integrates the nano-spinning functional modification process into the traditional spinning and drawing station, eliminating separate finishing processes such as film preparation, secondary coating, impregnation, and drying, thus shortening the production chain and simplifying the processing flow. The entire process can be directly adapted to existing spinning production lines for continuous operation, resulting in higher production efficiency, lower energy consumption and labor costs, and excellent industrial adaptability and scalability.

[0026] 3. Multi-field synergistic construction of a three-dimensional porous microstructure endows yarn with diverse functional properties. This invention utilizes the triple coupling effect of high-speed airflow turbulence, fiber dragging shearing, and solvent evaporation stress to stably form a three-dimensional crimped and interconnected porous network structure, which has a larger specific surface area and richer mass transfer channels compared to traditional dense encapsulated structures. By matching different functional polymer raw materials, multiple functions such as long-lasting antibacterial effect, efficient adsorption filtration, elastic self-healing, sweat conduction, and flexible sensing can be achieved, effectively broadening the application scenarios of the yarn.

[0027] 4. Wide range of raw material compatibility, strong process versatility, and large potential for industrialization. This invention is adaptable to various matrix short fibers and fiber-forming polymer systems, and can flexibly switch functional systems according to actual application needs to prepare a variety of functional yarns and fabrics. It can be widely applied to multiple fields such as smart wearable sensing, antibacterial protection, flexible self-healing, and adsorption filtration, with good process versatility and product scalability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the in-situ solution jetting nanofiber loaded spinning device at the drawing station of the present invention;

[0029] Figure 2 This is a top view schematic diagram of the spinning device for nanofiber load of the present invention;

[0030] Figure 3 This is a side view of the spinning device for nanofiber load of the present invention.

[0031] Figure 4 This is a partially enlarged schematic diagram of the multi-channel coaxial solution jet spinning nozzle of the present invention;

[0032] Figure 5This is a schematic cross-sectional view of the solution jet spinning gas-liquid two-phase jet forming principle of the present invention;

[0033] Figure 6 This is a photograph of the finished three-dimensional crimped nanofiber functional yarn bobbin obtained in Example 1 of the present invention.

[0034] Figure 7 This is a SEM microstructure image of the exogenous three-dimensional crimped nanofiber network on the surface of the yarn obtained in Example 1 of the present invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish an order. The term "multiple" means "two or more".

[0037] To facilitate understanding of the core device structure and nanofiber curling molding principle of this invention, in conjunction with the appendix... Figure 4 Appendix Figure 5 Explanation:

[0038] Figure 4 The diagram shows a partially enlarged view of the core jet nozzle, illustrating the arrangement of the slitting guide posts, spinning solution guide channels, high-pressure airflow annular channels, and coaxial spinneret micro-orifice array. Multiple fiber strips pass parallel through the nozzle guide area, and the polymer solution and high-pressure airflow are extruded simultaneously through the coaxial channels, ensuring that the nanofibers are uniformly deposited on the surface of each matrix fiber strip.

[0039] Figure 5 This is a schematic diagram of the cross-sectional principle of coaxial nozzle gas-liquid two-phase jet molding, with the polymer spinning solution channel, annular high-pressure airflow channel, gas / solution two-phase boundary, and air jet boundary marked respectively. The high-pressure airflow stretches, tears, and pulls the extruded polymer jet. Under the triple coupling of airflow turbulence, drag shear, and solvent evaporation internal stress, the nanofibers are induced to form a three-dimensional curled micromorphology, which explains the molding mechanism of the nanofiber curled structure of the present invention.

[0040] in, Figure 7The image, taken with a 7000x scanning electron microscope (SEM), clearly shows the exogenous nanofibers deposited on the surface of the matrix yarn entangled with each other and spontaneously forming a continuous, interconnected three-dimensional crimped porous network structure. This structure has a high specific surface area and porous permeation channels, which is the microstructure basis for the yarn to achieve multiple functions such as sensing, adsorption, and antibacterial properties. It also confirms the technical effect of triple mechanical coupling-induced crimping.

[0041] like Figures 1 to 7 As shown, this invention discloses an online continuous spinning method for preparing three-dimensional crimped nanofiber functional yarns. The method includes pre-spinning processes such as fiber raw material selection, opening and cleaning, carding, sliver forming, and drawing and drafting, as well as subsequent spinning and forming processes. Its core improvement lies in integrating the nanofiber spinning and loading process in situ into the bundling area of ​​the drawing frame, simultaneously completing the in-situ coating and composite modification of nanofibers within the conventional spinning process, achieving integrated online functional modification preparation of ordinary matrix yarns. The specific process steps are as follows:

[0042] (1) Preparation of solution jet spinning solution: Select a suitable fiber-forming polymer, completely dissolve it in the corresponding matching solvent, and after thorough stirring and standing to remove bubbles, obtain a uniform spinning solution with uniform composition, stable system, and can be directly used for solution jet spinning. The mass fraction of the fiber-forming polymer in the spinning solution is 3-45 wt%; the fiber-forming polymer can be selected from at least one of cellulose, chitosan, polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyetheretherketone (PEEK), polyethersulfone (PES), polyurethane (PU), polyamide (PA), and polyvinylamide; the solvent used is N,N-dimethylformamide (DMF) or deionized water.

[0043] (2) Preparation and delivery of matrix fiber sliver: Cotton staple fiber, viscose staple fiber or polyester chemical fiber staple fiber are selected as yarn matrix raw materials. After conventional cotton blending, opening and cleaning, and carding pre-spinning processes, a uniform and flat carded sliver is prepared. The carded sliver is fed into the drawing frame and smoothly delivered to the roller drafting area by the feeding mechanism for drafting and carding, which effectively improves the fiber straightness and sliver uniformity. The processed fiber sliver is uniformly delivered to the bundling area of ​​the drawing frame, ready to complete the nanofiber coating and composite processing.

[0044] (3) In-situ spinning and coating at the drawing frame: The prepared spinning solution is introduced into the solution jet spinning device, and nanofibers are continuously prepared by traction and stretching through high-pressure and high-speed airflow. The solution jet spinning device is fixedly installed directly above the bundling mechanism of the drawing frame, and the vertical installation height between it and the dynamically running fiber strip in the bundling area is controlled at 30-100cm. The entire spinning process parameters are precisely defined as follows: jet air pressure 0.05-0.25MPa, spinning solution extrusion speed 0.01-0.6mL / min, spinneret orifice inner diameter 0.10-0.80mm, spinning environment temperature 15-35℃, and spinning environment relative humidity 30%-65%.

[0045] During the in-situ spinning coating process, nascent nanofibers spontaneously form a well-structured and morphologically stable three-dimensional crimped microstructure under the synergistic effects of high-speed airflow turbulence, dragging shear force of the traveling fiber sliver, and micro-stress from rapid solvent evaporation. This structure is then uniformly and directionally deposited onto the surface of the continuously moving matrix fiber sliver, resulting in a nanofiber / matrix fiber composite fiber sliver. After being gathered and integrated by a bundler, the composite fiber sliver undergoes one to two drawing processes for mechanical compaction. This promotes deep embedding and anchoring of the surface three-dimensional crimped nanofibers within the gaps between the matrix fibers, significantly strengthening the interfacial bonding strength. Finally, it is fed into subsequent spinning and forming processes to complete drafting, twisting, and shaping, stabilizing the production of a three-dimensional crimped nanofiber functional yarn.

[0046] It should be noted that the subsequent spinning and forming process described in this invention can be any one of ring spinning, rotor spinning, vortex spinning, or air-jet spinning. The process is highly versatile and adaptable to various mainstream short-fiber yarn forming equipment. Besides the preferred ring spinning process, the composite fiber sliver of this invention can also be directly fed into a rotor spinning machine, vortex spinning machine, or air-jet spinning machine to complete yarn forming, thus producing functional yarns with a three-dimensional crimped nanofiber coating structure.

[0047] This invention also provides a three-dimensional crimped nanofiber functional yarn product obtained based on the above preparation method. The surface of this functional yarn forms a three-dimensional crimped porous network structure constructed from exogenous nanofibers. Unlike traditional yarns with simple surface bonding and floating layer attachment, the nanofibers are firmly bonded to the gaps in the matrix fiber surface through an interlocking and anchoring mechanism. Based on the anchoring effect of mechanical compaction during drawing, the yarn effectively avoids nanofiber peeling and shedding during subsequent spinning, weaving, and washing processes, exhibiting excellent structural stability and functional durability. Simultaneously, this three-dimensional crimped porous network has the structural advantages of a large specific surface area and well-developed pore structure, possessing excellent mass transfer and charge transport performance, making it suitable for wearable flexible sensing applications such as sweat monitoring.

[0048] This invention further provides functional fabrics woven from the aforementioned functional yarns. Based on the structural advantages of the functional yarns, these functional fabrics can be used to prepare various types of functional textiles, such as antibacterial fabrics, conductive sensing electronic fabrics, self-healing flexible fabrics, and high-adsorption filtration fabrics, according to the functional differences of the spinning polymer raw materials. These products exhibit good functional stability, wide applicability, high practical application value, and promising prospects for industrialization.

[0049] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0050] Example 1 (Low parameter range: Chitosan / pure cotton antibacterial functional yarn)

[0051] like Figure 1 , 2 As shown in Figures 3 and 4, this embodiment provides an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. The specific process steps are as follows:

[0052] (1) Preparation of solution for jet spinning: Chitosan was selected as the fiber-forming polymer and completely dissolved in deionized water. After thorough stirring and standing to remove bubbles, a uniform spinning solution with uniform composition and stable system was obtained. The mass fraction of chitosan in the spinning solution was 3wt%.

[0053] (2) Preparation and delivery of base fiber sliver: Pure cotton staple fiber is selected as the yarn base material. After conventional cotton blending, opening and cleaning, and carding pre-spinning processes, a uniform and flat carded sliver 2 is prepared. The carded sliver 2 is fed into the drawing frame and smoothly delivered to the roller drafting zone 3 by the feeding mechanism 1 for drafting and carding. After improving the fiber straightness and sliver uniformity, it is delivered at a uniform speed to the bundling zone 4 of the drawing frame to wait for operation.

[0054] (3) In-situ spinning and coating at the drawing frame: The prepared spinning solution is introduced into the solution jet spinning device described in this invention. The core jet nozzle 7 of this device is fixedly installed above the bundling mechanism of the drawing frame. The vertical installation height is selected as a conventional intermediate height within the range of 30-100cm. The spinning solution is transported to the nozzle from the internal supply tank 5 of the device, and solution jet spinning is completed by the jet airflow 6. The spinning process parameters are precisely controlled as follows: jet airflow pressure 0.05MPa, spinning solution extrusion speed 0.01mL / min, spinneret inner diameter 0.10mm, spinning environment temperature 15℃, and relative humidity 30%. Under the synergistic effect of high-speed airflow turbulence, fiber sliver drag shearing, and solvent evaporation internal stress, the nascent nanofibers spontaneously form a three-dimensional crimped microstructure (see Appendix for crimping mechanism). Figure 5The nanofibers are uniformly deposited and coated onto the surface of cotton fiber slivers to obtain nanofiber / cotton composite fiber slivers. After being bundled and gathered, the composite fiber slivers undergo two rounds of mechanical compaction and anchoring before being fed into the subsequent spinning and forming process to complete drafting and twisting. The subsequent spinning and forming process preferably adopts ring spinning technology, ultimately producing chitosan three-dimensional crimped nanofiber antibacterial functional yarn.

[0055] The physicochemical and antibacterial properties of the chitosan three-dimensional crimped nanofiber antibacterial functional yarn prepared in this embodiment were tested. The test results are as follows: the yarn breaking strength is 1.82 cN / dtex, and the hairiness value is 3.2 mm; after 50 water washing cycles, the nanofiber adhesion and retention rate on the yarn surface can reach 92.3%, and the antibacterial rate against Escherichia coli and Staphylococcus aureus is not less than 95%. The appearance of the finished yarn is detailed in the appendix. Figure 6 For details on the distribution of the three-dimensional coiled microporous network of exogenous nanofibers on its surface, please refer to the appendix. Figure 7 .

[0056] Example 2 (Medium parameter range: Polyacrylonitrile / viscose adsorption functional yarn)

[0057] This embodiment provides an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. The specific process steps are as follows:

[0058] (1) Preparation of solution for jet spinning: Polyacrylonitrile (PAN) was selected as the fiber-forming polymer and completely dissolved in DMF solvent. After thorough stirring and standing to remove bubbles, a uniform spinning solution with uniform composition and stable system was obtained. The mass fraction of polyacrylonitrile in the spinning solution was 12wt%.

[0059] (2) Preparation and delivery of matrix fiber sliver: Viscose staple fiber is selected as the yarn matrix raw material. After conventional cotton blending, opening and cleaning, and carding pre-spinning processes, a uniform and flat carded sliver 2 is prepared. The carded sliver 2 is fed into the drawing frame. After being drafted and sorted by the feeding mechanism 1 and the roller drafting zone 3, it is uniformly delivered to the bundling zone 4 of the drawing frame to wait for its turn.

[0060] (3) In-situ spinning and coating at the drawing frame: The prepared spinning solution is introduced into the solution jet spinning device described in this invention. The core jet nozzle 7 of this device is fixedly installed above the bundling mechanism of the drawing frame. The vertical installation height is selected as a conventional intermediate height within the range of 30-100cm. The spinning solution is transported to the nozzle from the internal supply tank 5 of the device, and solution jet spinning is completed by the jet airflow 6. The spinning process parameters are precisely controlled as follows: jet airflow pressure 0.15MPa, spinning solution extrusion speed 0.3mL / min, spinneret inner diameter 0.30mm, spinning environment temperature 20℃, and relative humidity 65%. Under the synergistic effect of multiple physical fields, the nanofibers form a regular three-dimensional crimped structure and are directionally deposited and coated on the surface of the viscose fiber strip to prepare a PAN nanofiber / viscose composite fiber strip. After being bundled and gathered, the composite fiber strips are mechanically compacted and anchored in two stages before being fed into the subsequent spinning and forming process to complete the drafting and twisting process. The subsequent spinning and forming process preferably adopts the ring spinning process, and finally produces a high specific surface area adsorption functional yarn.

[0061] This embodiment relies on a three-dimensional crimped porous network constructed from PAN nanofibers to form a large number of interconnected micro- and nano-pores on the surface of the yarn. Based on the microstructural characteristics, the yarn is expected to have a large specific surface area, enabling it to adsorb and retain dust, volatile gases, and trace amounts of harmful substances. With the help of mechanical extrusion and anchoring in the drawing process, the nanofibers and viscose matrix fibers interlock and interlock, which can effectively prevent fiber peeling during subsequent weaving and washing processes. It has good functional stability and can be used to prepare functional fabrics for filtration and environmental adsorption.

[0062] Example 3 (High parameter range: polyurethane / polyester elastic functional yarn)

[0063] This embodiment provides an online continuous yarn forming method for preparing three-dimensional crimped nanofiber functional yarns. The specific process steps are as follows:

[0064] (1) Preparation of solution for jet spinning: Polyurethane (PU) is selected as the fiber-forming polymer and completely dissolved in deionized water. After thorough stirring and standing to remove bubbles, a uniform spinning solution with uniform composition and stable system is obtained. The mass fraction of polyurethane in the spinning solution is 45 wt%.

[0065] (2) Preparation and delivery of matrix fiber sliver: Polyester staple fiber is selected as the yarn matrix raw material. After conventional cotton blending, opening and cleaning, and carding pre-spinning processes, a uniform and flat carded sliver 2 is prepared. After being fed into the drawing frame and drafted, it is uniformly delivered to the bundling area 4 to wait for its turn.

[0066] (3) In-situ spinning and coating at the drawing frame: The prepared spinning solution is introduced into the solution jet spinning device described in this invention. The core jet nozzle 7 of this device is fixedly installed above the bundling mechanism of the drawing frame. The vertical installation height is selected as a conventional intermediate height within the range of 30-100cm. The spinning solution is transported to the nozzle from the internal supply tank 5 of the device, and solution jet spinning is completed by the jet airflow 6. The spinning process parameters are precisely controlled as follows: jet airflow pressure 0.25MPa, spinning solution extrusion speed 0.6mL / min, spinneret inner diameter 0.80mm, spinning environment temperature 35℃, and relative humidity 65%. Under the synergistic effect of multiple physical fields, the nanofibers form a dense three-dimensional crimped structure and are directionally deposited and coated on the surface of the polyester fiber strip to prepare a polyurethane / polyester composite fiber strip. After being bundled and gathered, the composite fiber strips are mechanically compacted and anchored in two stages before being fed into the subsequent spinning and forming process to complete the drafting and twisting process. The subsequent spinning and forming process preferably adopts the ring spinning process, and finally produces a highly elastic, self-healing three-dimensional crimped nanofiber functional yarn.

[0067] Polyurethane material itself has excellent elasticity and microscopic self-healing properties. When combined with the deformation recovery space of the three-dimensional crimped fiber network, the tensile recovery ability, softness and wear resistance of the finished yarn can be significantly improved. The crimped structure is mechanically locked in the gap of the polyester matrix, the interface bonding is reliable, and it is not easy to fail under repeated bending and washing conditions. It is suitable for weaving flexible wear-resistant fabrics and wearable sweat monitoring flexible sensor electronic fabrics.

[0068] To fully verify the innovativeness of the process, the rationality of the parameters, and the structural advantages of the present invention, three sets of control experiments were set up, corresponding to the traditional stepwise composite process, the parameter over-limit process, and the blank process without in-situ load, respectively, to verify the technical progress of the present invention from three dimensions: process mode, parameter range, and structural innovation.

[0069] Comparative Example 1 (Traditional finishing and compounding process)

[0070] Antibacterial functional yarn was prepared using a traditional two-stage composite process: the in-situ spinning loading process at the drawing station was eliminated. Pure cotton staple fibers were first prepared into pure cotton yarn through cotton blending, opening and cleaning, carding, drawing and subsequent spinning forming processes; then chitosan nanofiber membrane was prepared separately by solution jet spinning, and then attached to the surface of pure cotton yarn by coating and bonding in the later stage. The other raw materials and spinning parameters were completely consistent with those in Example 1.

[0071] Test results: The nanofibers are simply attached to the surface of the yarn without any mechanical interlocking structure; the breaking strength is 1.49 cN / dtex, and the yarn hairiness is 5.1 mm; after 50 washes, the nanofiber retention rate is only 65.2%, and the antibacterial rate drops to 68%. This process is lengthy and cannot achieve continuous online production; its functional durability is far lower than the in-situ loading method of this invention.

[0072] Comparative Example 2 (Control Group with Process Parameters Exceeding Limits)

[0073] Based on the raw materials and process flow of Example 2, only the core process parameters were adjusted beyond the scope of protection of this invention: jet air pressure 0.30MPa, spinning solution concentration 50wt%, and ambient temperature 40℃. The remaining processes, equipment, and raw materials were completely the same.

[0074] When the parameters exceed the limits, the stability of the spinning solution during stretching and molding deteriorates, the nanofibers vary greatly in thickness, and they are prone to agglomerating into coarse fiber bundles, making it impossible to form a continuous and regular three-dimensional crimped porous topology. The fiber bond with the matrix fiber strip is loose, and it can be predicted that the water wash resistance will decrease significantly. The lack of pore structure will directly lead to a significant decrease in adsorption and filtration performance, which confirms the rationality and necessity of the process parameter range defined in this invention.

[0075] Comparative Example 3 (Blank Control Group: Pure Matrix Yarn)

[0076] The solution jet in-situ spinning loading process was completely eliminated, and pure polyester ordinary yarn was prepared using only polyester staple fiber through the traditional full process as a blank control sample.

[0077] The surface of blank yarn lacks an external three-dimensional crimped nanofiber porous network, thus lacking additional adsorption capacity, microscopic self-healing ability, and charge conduction ability. It retains only the conventional mechanical properties of polyester yarn itself, which directly demonstrates the core role of the in-situ loading of three-dimensional crimped nanofiber structure in the yarn multifunctional upgrade at the drawing station.

[0078] Table 1 Comparison of nanofiber morphology and yarn properties between each embodiment and comparative example.

[0079] Example 1 Uniform three-dimensional curling, deep interlocking and anchoring Excellent water wash resistance and reliable long-lasting antibacterial properties Example 2 Regular three-dimensional curl with well-developed internal pores High specific surface area and excellent adsorption and filtration performance Example 3 Dense three-dimensional curled elastic network structure It has excellent elasticity and self-repair capabilities. Comparative Example 1 Flat surface bonding, no mechanical locking The fibers are easily washed away and shed, resulting in insufficient functional durability. Comparative Example 2 Uneven fiber thickness, locally clustered Poor molding consistency and significant reduction in additional functions Comparative Example 3 No exogenous nanofiber structure It only possesses the basic properties of polyester matrix yarn.

[0080] Table 1 above summarizes and compares the microstructure and corresponding functional effects of the nanofibers in each embodiment and comparative example. It can be seen that all three embodiments of the present invention, through in-situ solution jet spinning at the drawing station, utilize the synergistic effects of airflow turbulence, drag shear force, and solvent evaporation internal stress to stably construct a well-formed three-dimensional crimped nanofiber network. Multiple drawing and mechanical compaction processes then achieve the interlocking and anchoring of the fibers and matrix, resulting in high interfacial bonding strength. Specifically, Embodiment 1 forms a uniformly interlocked three-dimensional crimped structure, giving the finished yarn excellent wash resistance and long-lasting antibacterial durability; Embodiment 2 forms a well-pored three-dimensional crimped network structure, relying on its high specific surface area to endow the yarn with excellent adsorption and filtration capabilities; Embodiment 3 uses a polyurethane-based dense elastic crimped network, providing the yarn with excellent tensile resilience and microstructural self-healing properties.

[0081] In contrast, all three comparative examples have obvious defects: Comparative Example 1 uses a traditional finishing and bonding process, where the nanofibers are only flatly attached to the surface of the yarn, lacking a mechanical locking and anchoring structure. The fibers are easy to fall off during washing, resulting in poor functional durability. Comparative Example 2 uses process parameters that exceed the scope of this invention, resulting in poor uniformity of nanofiber formation, uneven thickness, and localized agglomeration. It cannot form continuous and interconnected functional pores, significantly reducing its additional performance. Comparative Example 3 is a pure matrix yarn without exogenous nanofibers. It does not have a three-dimensional crimped porous topology and only retains the conventional properties of the matrix fibers themselves, lacking extended functions such as adsorption, flexible sensing, and self-healing.

[0082] Through multiple sets of horizontal comparisons, the online coupling spinning process, multi-field collaborative crimping and forming mechanism, and drawing and compaction anchoring structure defined in this invention have been fully verified. These features play a key role in improving the structural stability of functional yarns and endowing yarns with diversified additional functions. The technical solution has outstanding advantages and practicality.

[0083] In summary, based on the above-mentioned process and structural improvements, this invention has significant technical advantages over the prior art in several aspects, as follows:

[0084] 1. Mechanically locked and anchored structure enhances yarn stability and improves washability and long-term service performance. This invention utilizes multiple drawing and mechanical compaction processes to embed three-dimensional crimped nanofibers into the gaps between the matrix fibers. The crimped configuration creates a physical locking and anchoring effect, which to some extent improves the weak interfacial bonding of traditional finishing and coating methods. This reduces the likelihood of functional layer failures such as peeling, detachment, and pilling during washing, friction, and weaving. After 50 wash cycles, Example 1 showed a nanofiber retention rate of 92.3%. The yarn maintained good structural integrity during repeated stretching, rubbing, and weaving, helping to alleviate the problems of insufficient durability and gradual functional degradation after repeated use in traditional nanocomposite yarns.

[0085] 2. Multi-stage collaborative in-situ molding simplifies the processing flow, facilitating continuous production and controlling manufacturing costs. This invention integrates the solution-jet nanofiber spinning process into the spinning and drawing station, completing in-situ nanofiber coating while the matrix fibers are forming slivers. This eliminates the need for separate nanofiber membrane preparation, secondary coating, and subsequent dip-coating processes, shortening the overall processing chain and reducing intermediate transfer and equipment investment. This process is adaptable to various existing spinning production lines for continuous operation. Compared to stepwise compounding and offline modification methods, it offers advantages in production efficiency, labor, and energy costs, demonstrating significant potential for industrial-scale application.

[0086] 3. Three-dimensional crimped porous microstructure expands yarn's additional functions and enriches product application scenarios. A three-dimensional crimped nanonetwork formed under the combined effects of airflow turbulence, fiber drag shear force, and solvent evaporation internal stress can construct a high-specific-surface-area interconnected micro-nano pore structure on the yarn surface. Depending on the type of fiber-forming polymer used, additional properties such as long-lasting antibacterial properties, trace pollutant adsorption and filtration, elastic recovery and micro-self-repair, sweat wicking, and flexible conductive sensing can be imparted to the yarn. Simultaneously, the crimped fibers possess a certain degree of deformation resilience, without adversely affecting the subsequent weaving performance of the base yarn. It can be used to process antibacterial protective fabrics, air filtration fabrics, and can also be woven into wearable flexible electronic fabrics for sweat monitoring. A functional yarn substrate adaptable to multiple applications can be obtained through the same preparation process.

[0087] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. An online continuous spinning method for preparing three-dimensional crimped nanofiber functional yarns, comprising a pre-spinning process of fiber raw material selection, opening and cleaning, carding, carding into slivers, drawing and drafting into slivers, and a subsequent spinning and forming process, characterized in that: In-situ loading of nanofibers in the bundling zone of the drawing frame during the drawing process, the specific steps are as follows: (1) Preparation of solution for jet spinning: Dissolve the fiber-forming polymer in the corresponding solvent and stir thoroughly until the system is homogeneous and stable to obtain the spinning solution; (2) Preparation and delivery of matrix fiber sliver: The carded sliver obtained from the previous spinning process is fed into the drawing frame and then sent to the bundling area for waiting through the feeding mechanism and the roller drafting zone; (3) In-situ spinning and coating at the drawing station: The spinning solution obtained in step (1) is spun into nanofibers using a solution jet spinning device; the nanofibers form a three-dimensional crimped structure under the synergistic effect of high-speed airflow turbulence, drag shear force of the moving fiber strip, and internal stress of solvent evaporation, and are directionally deposited and coated on the outer surface of the running fiber strip to obtain a nanofiber / matrix fiber composite fiber strip; after the composite fiber strip is bundled and gathered, it is subjected to 1 to 2 drawing and compaction to strengthen the interface bonding, and then twisted and shaped by subsequent spinning and forming processes to obtain a three-dimensional crimped nanofiber functional yarn.

2. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: In step (1), the spinning solution contains a fiber-forming polymer with a mass fraction of 3-45 wt%; the fiber-forming polymer is at least one of cellulose, chitosan, polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyether ether ketone (PEEK), polyether sulfone (PES), polyurethane (PU), polyamide (PA), and polyvinylamide; the solvent used is N,N-dimethylformamide (DMF) or deionized water.

3. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: Step (2) The matrix short fiber raw material after pre-spinning is cotton short fiber, viscose short fiber or polyester chemical fiber short fiber.

4. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: In step (3), the solution jet spinning device is fixedly installed directly above the bundling mechanism of the drawing frame, and the device is installed vertically to the fiber strip in the bundling area at a height of 30 to 100 cm.

5. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: The process parameters for solution jet spinning in step (3) are as follows: jet gas pressure 0.05~0.25MPa, spinning solution extrusion speed 0.01~0.6mL / min, spinneret inner diameter 0.10~0.80mm, spinning environment temperature 15~35℃, and spinning environment relative humidity 30%~65%.

6. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: In the prepared nanofiber functional yarn, the exogenous nanofibers are embedded in the gaps of the matrix fiber surface in a three-dimensional crimped form and anchored by mechanical extrusion during drawing, making them difficult to peel off during spinning, weaving and washing processes; the three-dimensional crimped structure is independently formed by exogenous jet nanofibers.

7. The method for online continuous yarn forming of three-dimensional crimped nanofiber functional yarn according to claim 1, characterized in that: The subsequent spinning and forming process can be any one of ring spinning, rotor spinning, vortex spinning, or air-jet spinning.

8. A three-dimensional crimped nanofiber functional yarn, characterized in that, Prepared by the method described in any one of claims 1 to 7.

9. A functional fabric, characterized in that, The fabric is woven from the three-dimensional crimped nanofiber functional yarn as described in claim 8; the fabric is an antibacterial fabric, a conductive sensing electronic fabric, a self-healing flexible fabric, or a high-adsorption filtration fabric.

Images